Three-dimensional micro-scale strain mapping in living biological soft tissues.

Area of Science:

• Biomedical Engineering
• Cellular Mechanics
• Biomaterials Science

Background:

• Understanding cellular mechanical micro-environments is crucial for cell biosynthesis and phenotype regulation.
• Current imaging methods lack the capability for 3D characterization of cellular micro-environments in biological tissues.
• Multi-photon laser microscopy offers potential for high-resolution, non-invasive imaging of tissue mechanics.

Purpose of the Study:

• To develop a multi-photon laser microscopy protocol for imprinting 3D grid lines in living tissues.
• To create image processing software for high-resolution 3D strain analysis.
• To enable non-invasive, multi-scale mechanical characterization of biological tissues.

Main Methods:

• Developed a novel two-photon excitation imaging technique for 3D internal kinematics measurement in articular cartilage.
• Utilized custom image processing software (lsmgridtrack) for accurate 3D micro-strain analysis.
• Applied the technique to intact cartilage, achieving sub-micrometer resolution across tissue and cellular length scales.

Main Results:

• Successfully measured 3D kinematics within intact cartilage at sub-micrometer resolution.
• Provided robust and accurate 3D micro-strain analysis for detailed kinematic assessment.
• Demonstrated preservation of tissue structural integrity post-scanning for longitudinal studies.

Conclusions:

• The novel imaging technique allows for non-invasive, multi-scale mechanical characterization of biological tissues.
• This approach enhances understanding of cell mechano-transduction and its role in soft connective tissue adaptation and degeneration.
• The technique is versatile and applicable to various tissues, including cartilage, meniscus, annulus fibrosus, and engineered tissues.